1. Field of the Invention
The present invention relates generally to analyzers used for analyzing components of samples.
2. Description of the Background Art
Conventionally, components of samples such as blood, interstitial fluid, urine, spinal fluid, and saliva are analyzed by, for example, absorbance measurement using an analysis tool called a biochip (or a microchip). The biochip is provided with minute analytical cells with diameters of around 1 mm or smaller and generally is configured with an optically transparent plate-like member bonded thereto (see, for example, JP 2007-163344 A and JP 2007-170943 A).
Specifically, the biochip is composed of an optically transparent substrate (transparent substrate) and an optically transparent cover for covering the transparent substrate. In the transparent substrate, minute concave portions to serve as cells and grooves to serve as minute channels for supplying a sample are formed. Furthermore, various reagents are placed in the respective cells of the biochip. When a sample is supplied into the cells through the channels, the reagents react with specific components in the sample and thereby colors are developed.
Furthermore, with respect to such a biochip, absorbance measurement is performed with an analyzer (see, for example, JP 2007-163344 A and JP 2007-170943 A). Specifically, the analyzer contains a light source unit that emits light and a light-receiving unit that receives light emitted from the light source unit. The biochip is inserted into the analyzer through an insertion opening thereof and is positioned so that a cell is located between the light source unit and the light-receiving unit.
Light emitted from the light source unit is incident on a cell. Part of the incident light is absorbed by the cell while the rest is transmitted therethrough to be received by the light-receiving unit. The analyzer calculates absorbance from the transmitted light that was received by the light-receiving unit. Furthermore, the concentration of a specific component contained in the sample is calculated from the absorbance. The concentration thus calculated is displayed on a display connected to the analyzer.
In order to improve the accuracy of absorbance calculation, it is necessary to optimize the positional relationship among the light source unit, the light-receiving unit, and a cell so that light emitted from the light source unit is incident on the cell properly and light transmitted through the cell is incident on the light-receiving unit properly. In this case, when the analyzer is configured so that the positional relationship among the three members are optimized by moving the light source unit and the light-receiving unit, the configuration of the analyzer is complicated and the cost increases.
Accordingly, analyzers employ the configuration in which the positional relationship among the three members are optimized by fixing the positions of the light source unit and the light-receiving unit and accurately placing a biochip in the predetermined position. For example, analyzers described in JP 2007-163344 A and JP 2007-170943 A each contain a member that comes into contact with one end of the microchip to position it. A user only needs to insert the microchip so that a part of the microchip comes into contact with the member.
However, the configuration in which the above-mentioned biochip is inserted through the insertion opening and is positioned by means of contact has a problem in that operational error made by the user tends to cause displacement since the cell is minute.
Furthermore, recently, a disk-shaped biochip has been proposed. In this biochip, a plurality of cells are arranged along an arc. When using a disk-shaped biochip, optical measurement can be performed with respect to each cell while the biochip is rotated, which allows efficient analysis to be performed. In such a disk-shaped biochip, however, it is difficult to position it by means of contact. Accordingly, the above-mentioned problem becomes further pronounced.